Sources said the balaclava-clad men shot dead two police officers at the African Inland Church (AIC) and used their guns to shoot the worshippers.

They also hurled grenades into the churches. The twin attacks on the Our Lady of Consolata Catholic Church and the Garissa AIC took place around 10.20am.

In the first instance, three men drove into the AIC compound, two alighted from the vehicle and walked towards the police officers who were seated about 20 metres from the church.

They shot them dead with pistols at close range. They then took their firearms, two AK47 rifles loaded with 60 rounds of ammunition, and fired several shot in the air — forcing the congregation to rush towards the back door for safety.

They then hurled two grenades into the church and opened fire indiscriminately, killing nine worshippers on the spot.

They escaped in their car. The bodies of the victims lay in a heap at the back door of the church, an indication that they were trying to escape from the executioners. Most of them were shot in the head.

One of the police officers was identified as Issa Mohammed Aden, who was recently transferred from the Diplomatic Police Unit in Nairobi.

He was buried a few hours after the attack at the Technical Muslim Cemetery. The identity of the other officer was withheld until the next of kin are notified of his death.

Around the same time, another group hurled two grenades at the Catholic Church but one did not explode. Mr Daniel Munyasia, a guard on duty, said the attackers escaped on foot into a waiting vehicle.

This came as security forces scoured the porous border with war-torn Somalia in search of four aid workers kidnapped from Dadaab refugee camp on Friday.

“The search is intensifying and more security forces have been sent to make every effort possible, but so far no one has been recovered,” the army spokesman Cyrus Oguna told AFP.

The North Eastern deputy police boss Philip Ndolo said at least two officers are deployed to guard places of worship in the town on Sundays.

The Vatican termed the twin attacks a ‘horrible and very worrying’ act. “Among terrorist groups, attacks on Christians gathered on Sunday in their place of worship has become a method, believed to be particularly efficient, of spreading hatred and fear.

''The cowardice of the violence against helpless people gathered peacefully for prayer is unspeakable,” spokesman Federico Lombardi told Vatican Radio.

In Nairobi, Police Spokesman Eric Kiraithe put the death toll at 14, although Nation reporters counted 16 bodies at the scene.

“Twelve worshipers including nine women were killed. Two police officers on patrol around the AIC were also killed in the attack,” he said.

Mr Ndolo said all the dead were at the AIC service, where more than 63 people were also injured. The blast at Catholic church hurt three people. The injured were taken to the Garissa Provincial General Hospital.

Another worshipper, Mr Felix Kimanzi, said the masked gunmen wore blue uniforms. “I was 100 metres away from the church when I saw two gunmen at the entrance spray bullets at the congregation. I hid from their sight,” he said.

On Monday, seven officers from Scotland Yard’s Counter Terrorism Command are expected in the country to hunt for a British woman linked to the June 24 attack at Jericho Beer Garden in Mombasa where three people were killed in a grenade attack and scores injured last Sunday.

Samantha Lewthwaite, 28, is wanted for possessing explosives and conspiring to make bombs. Meanwhile, Prime Minister Raila Odinga has cancelled a meeting scheduled for Monday with permanent secretaries and will instead lead a government security team to Garissa.

Vice-President Kalonzo Musyoka condemned the attacks. Cabinet minister Mohamed Elmi said the attackers intend to create a religious rift between Christians and Muslims.

“We will not be divided by those who want to create fear within us,” Mr Elmi said.

The Supreme Council of Kenya Muslims chairman, Prof Abdulghafur El-Busaidy, condemned the attacks, saying, places of worship should be respected by all. “We detest such acts and as Supkem, we are condemning the act from the bottom of our hearts,” he said.